CN103643230A - Surface treatment method for composite sulfuric acid-phosphomycin calcium applicable to warm extrusion - Google Patents

Abstract

The invention relates to the field of metal surface treatment, especially suitable for warm extrusion of ferrous metals. It is necessary to perform surface treatment on ferrous metal blanks with a composite sulfuric acid-phosphate solution to obtain a layer of composite sulfuric acid-calcium phosphate film capable of high temperature resistance. Used to increase mold life. Calcium oxide CaO ultrafine powder, calcium sulfate CaSO4 ultrafine powder, calcium dihydrogen phosphate Ca(H2PO4)2 ultrafine powder, phosphoric acid H3PO4, sulfuric acid H2SO4 and distilled water H2O are proportioned in proportion, and compound calcium sulfate CaSO4 and phosphoric acid are formed through the reaction. Calcium dihydrogen Ca (H2PO4) 2 salt solution, the billet is subjected to shot blasting, pickling, phosphating of the above solution, dehydrogenation and saponification to obtain a ferrous metal extrusion billet with a composite sulfuric acid-calcium phosphate salt surface film.

Description

A Composite Sulfuric Acid-Calcium Phosphate Salt Surface Treatment Method Adapted to Warm Extrusion

technical field

The invention relates to the field of metal surface treatment, especially suitable for warm extrusion of ferrous metals. It is necessary to perform surface treatment on ferrous metal blanks with a composite sulfuric acid-phosphate solution to obtain a layer of composite sulfuric acid-calcium phosphate film capable of high temperature resistance. Used to increase mold life.

Background technique

At present, the application of metal surface treatment by phosphating solution is very extensive, and the demand for phosphating metal surface for extrusion industry is very large. In the early 20th century, due to the invention of tool steel and metal surface phosphating technology, the extrusion of ferrous metals was realized. The extrusion of ferrous metals was first used in military industry. The most typical product is bullet casings. In the 1950s, ferrous metals Extrusion began to be used in civilian use, and is currently widely used in the field of auto parts manufacturing. The process of forming a phosphate film on the surface of the workpiece has been well applied as a key technology to realize the extrusion of ferrous metals.

For the phosphating solution suitable for ferrous metal extrusion, it is required to form a phosphate film on the surface of the workpiece through the phosphating solution. The thickness of the film is generally 10-15 μm, and the friction coefficient is about 0.05. The formed phosphate film is composed of fine flaky crystal structures. It is required that the film layer is quite soft, heat-resistant, porous, has a strong adsorption effect on lubricants, and has a certain degree of plasticity, which can be plastically deformed together with the workpiece. Therefore, the role of the phosphating layer is an isolation cushion between the mold and the workpiece, which reduces surface friction and improves the life of the mold. However, since the phosphating layer prepared by the traditional phosphating solution is usually suitable for cold extrusion, the phosphating layer usually begins to decompose when the working temperature is higher than 200°. For warm extrusion of ferrous metals, the general temperature is slightly lower than the recrystallization temperature of ferrous metals. For example, the warm extrusion temperature of steel is generally around 900°. At this time, the phosphating layer is destroyed, and satisfactory lubrication cannot be obtained during the extrusion process. Greatly reduces the life of the mold.

Therefore, based on the above-mentioned purpose, a kind of ferrous metal provided by the present invention is carried out warm extrusion, needs to carry out surface treatment to ferrous metal blank by composite sulfuric acid-calcium phosphate solution, obtains a layer of composite sulfuric acid-calcium phosphate salt film capable of high temperature resistance, adopts The composite sulfuric acid-calcium phosphate film formed by the method can withstand high temperature, and the composite sulfuric acid-calcium phosphate film has a strong ability to adhere to workpieces during the extrusion process, can greatly improve the life of a mold, and has very important industrial application value.

Contents of the invention

The purpose of the patent of the present invention is to solve the technical deficiency of warm extrusion phosphating layer decomposition, to provide surface composite sulfuric acid-calcium phosphate film with strong adhesion ability, high temperature resistance and no decomposition, low production cost, no pollution emission, and can be used in conventional warm extrusion It is a surface treatment method suitable for warm extrusion of ferrous metals produced under pressure conditions. Compared with the traditional zinc phosphate film, it can withstand high temperature and have better stability.

The technical solution of the patent of the present invention is: the present invention is a composite sulfuric acid-calcium phosphate surface treatment method suitable for ferrous metal warm extrusion, as follows:

The compound sulfuric acid-calcium phosphate salt solution suitable for ferrous metal warm extrusion in the present invention includes calcium oxide CaO ultrafine powder, calcium sulfate CaSO ₄ ultrafine powder, calcium dihydrogen phosphate Ca(H ₂ PO ₄ ) ₂ ultrafine powder , phosphoric acid H ₃ PO ₄ , sulfuric acid H ₂ SO ₄ and distilled water H ₂ O, the mass ratio is: (5-10): (15-30): (40-60): (10-30): (5 -10) (808:912):

CaO+2H ₂ O=Ca(OH) ₂ Ca(OH) ₂ + H ₂ SO ₄ = CaSO ₄ +2H ₂ O

Ca(OH) ₂ + 2H ₃ PO ₄ = Ca(H ₂ PO ₄ ) ₂ +2H ₂ O

The composite sulfuric acid-calcium phosphate salt produced by the invention is a layer of salt film of CaSO ₄ and Ca(H ₂ PO ₄ ) ₂ and can be adapted to warm extrusion of ferrous metals.

The method for the compound sulfuric acid-calcium phosphate surface treatment that is used for ferrous metal blank warm extrusion of the present invention:

The first step: Spheroidize the blank after blanking, and the heating temperature should be lower than the recrystallization temperature of the material below 50°C for 3-4 hours;

Step 2: Shot peen the blank for 15 minutes with a shot blasting machine to remove fine burrs on the surface of the blank and strengthen the surface quality;

The third step: pickling, using 2% sulfuric acid solution for pickling;

The fourth step: put the blank to be processed into the compound sulfuric acid-calcium phosphate salt solution at 55°-60°C for 5-10min;

Step 5: Carry out heating and dehydrogenation process to reduce the harm of hydrogen embrittlement;

Step 6: Carry out the saponification process to further enhance the lubrication between the extrusion billet and the die.

Compared with the prior art, the present invention has the following advantages

(1) Suitable for warm extrusion of ferrous metals: the composition of the obtained phosphating layer is composite sulfuric acid-calcium phosphate salt, which generally decomposes above 1500°, can withstand high temperature without decomposing, and meets the requirements of warm extrusion of ferrous metals.

(2) Low cost: The raw materials used are all basic chemical products, which are low in price and meet the requirements of large-scale industrial applications.

(3) Easy to operate: The present invention can use traditional phosphating and saponification process equipment without major changes, and the operation is simple and reliable.

(4) Short phosphating time and good effect: After the billet is coated with calcium salt, the film layer is soft, heat-resistant, porous, has a strong adsorption effect on lubricants, and has certain plasticity. The phosphating time is short, The effect is good.

Detailed ways

Provide the preferred embodiment of the present invention below:

Spheroidizing and annealing the blank after cutting, the heating temperature should be lower than the recrystallization temperature of the material below 50°C and keep warm for 3-4 hours; the blank is shot peened for 15 minutes by a shot blasting machine to remove the fine burrs on the surface of the blank and strengthen Surface quality; carry out pickling, adopt 2% sulfuric acid solution to carry out pickling; Provide the chemical composition ratio according to the invention, configure a kind of composite sulfuric acid-calcium phosphate surface treatment solution suitable for ferrous metal warm extrusion: including calcium oxide CaO , calcium sulfate CaSO ₄ , calcium dihydrogen phosphate Ca(H ₂ PO ₄ ) ₂ , phosphoric acid H ₃ PO ₄ , sulfuric acid H ₂ SO ₄ and distilled water H ₂ O, the mass ratio is: (5-10): ( 15-30): (40-60): (10-30): (5-10) (808:912). In this embodiment, its mass ratio can be selected from any of the following: 5:15:40:10:5:808; 10:30:60:30:10:912; 8:20:45:15:8 :830; 9:25:50:20:9:880. Put the blank to be treated in a composite sulfuric acid-calcium phosphate salt solution at 55°-60°C for 5-10 minutes; perform a heating dehydrogenation process to reduce the harm of hydrogen embrittlement. The saponification process is carried out to further enhance the lubrication between the extrusion billet and the die.

Claims (3)

1. A compound sulfuric acid-calcium phosphate salt surface treatment method adapting to warm extrusion is characterized in that it utilizes calcium oxide CaO superfine powder, calcium sulfate CaSO superfine powder, calcium dihydrogen phosphate Ca(H2PO4) superfine powder, Phosphoric acid H3PO4, sulfuric acid H2SO4 and distilled water H2O are proportioned in proportion, and the compound calcium sulfate CaSO4 and calcium dihydrogen phosphate Ca(H2PO4)2 salt solution are formed through the reaction. and saponification, i.e. obtaining a ferrous metal extrusion billet with a complex sulfuric acid-calcium phosphate surface film: (a) The composition ratio of the composite sulfuric acid-calcium phosphate salt solution for ferrous metal warm extrusion: including calcium oxide CaO ultrafine powder, calcium sulfate CaSO ₄ ultrafine powder, calcium dihydrogen phosphate Ca(H ₂ PO ₄ ) ₂ ultrafine Fine powder, phosphoric acid H ₃ PO ₄ , sulfuric acid H ₂ SO ₄ and distilled water H ₂ O, the mass ratio is: (5-10): (15-30): (40-60): (10-30): (5-10) (808:912); (b) The composite sulfuric acid-calcium phosphate salt produced by the present invention is a layer of salt film of CaSO ₄ and Ca(H ₂ PO ₄ ) ₂ , which can withstand high temperature of 1500° and is suitable for warm extrusion of ferrous metals. 2. A kind of composite sulfuric acid-calcium phosphate surface treatment method suitable for warm extrusion according to claim 1 is characterized in that the cost is low and the process is easy to operate: the raw materials used are all basic chemical products, which are cheap and meet the requirements of large Large-scale industrial application requirements; at the same time, without major process changes, traditional phosphating and saponification process equipment can be used, and the operation is simple and reliable. 3. A kind of composite sulfuric acid-calcium phosphate surface treatment method adapting to warm extrusion according to claim 1, characterized in that: after the blank adopts calcium salt coating, the film layer is soft, high temperature resistant, and porous, The lubricant has a strong adsorption effect, and has a certain degree of plasticity. The phosphating time is short and the effect is good.